GE SafetyNet Modules – 8851-LC-MT

Technical Dossier

Product Details And Specifications

GE SafetyNet Series Technical Notes

The Evolution of SafetyNet Architecture

The SafetyNet platform was introduced by GE Fanuc in the early 1990s as a response to industry demand for an integrated safety shutdown system (SIS) that could coexist with standard DCS and PLC infrastructure. The original architecture used a VME-based backplane with dedicated safety-rated I/O modules and a proprietary communication bus. Early versions operated on the Series 90-70 hardware foundation, sharing physical form factors but maintaining logically isolated safety execution environments.

In subsequent generations, GE introduced the 8851-series controller family, which standardized the CPU and logic controller modules under a unified SafetyNet designation. These modules introduced dual-channel redundancy, watchdog timer circuits, and cross-checking diagnostics between primary and secondary processors. Communication adapters were added to support Modbus RTU, Ethernet TCP/IP, and proprietary GE SRTP protocols, enabling integration with plant-wide SCADA and historian systems.

As the platform matured into the 2000s, GE transitioned support to Emerson (following the GE Automation divestiture) and later to Emerson's DeltaV SIS product line as the recommended migration path. The SafetyNet series is now classified as a mature/end-of-life platform. GE and Emerson have ceased active development, and original equipment manufacturer (OEM) support for many modules has been discontinued. Sites operating SafetyNet systems must rely on third-party MRO suppliers and certified repair facilities for ongoing spare parts and lifecycle extension support.

SafetyNet Full Catalog & Functionalities (SKU List)

The following SKUs represent verified, commonly sourced modules within the GE SafetyNet platform. Each entry includes a concise functional description for engineering reference.

Logic Controllers & CPUs

• 8851-LC-MT: SafetyNet logic controller, SIL 2/3 rated, dual-channel redundant CPU module
• 8851-LC-MT-2: Enhanced logic controller with expanded memory and faster scan cycle
• 8851-LC-ST: Simplex logic controller variant for non-redundant safety applications
• 8851-CPU-001: Base CPU module, Series 90-70 compatible SafetyNet processor

Digital Input (DI) Modules

• 8851-DI-115: 16-channel 115VAC digital input module, SIL 2 rated
• 8851-DI-024: 16-channel 24VDC digital input module with diagnostics
• 8851-DI-048: 32-channel 48VDC digital input, high-density safety I/O
• 8851-DI-125: 8-channel 125VDC digital input for substation-grade applications

Digital Output (DO) Modules

• 8851-DO-024: 8-channel 24VDC digital output, solid-state, SIL 2 rated
• 8851-DO-115: 8-channel 115VAC relay output module with contact monitoring
• 8851-DO-RLY: 8-channel relay output module, dry contact, 250VAC rated

Analog Input (AI) Modules

• 8851-AI-420: 8-channel 4–20mA analog input, 12-bit resolution, SIL 2
• 8851-AI-VLT: 8-channel voltage analog input, ±10V range, isolated channels

Communication & Network Adapters

• 8851-CMM-001: SafetyNet communication module, Modbus RTU / SRTP gateway
• 8851-ETH-001: Ethernet TCP/IP adapter for SafetyNet backplane integration

Power Supply Modules

• 8851-PSU-024: 24VDC redundant power supply module for SafetyNet rack
• 8851-PSU-115: 115VAC input power supply, single-slot, rack-mounted

Quality Control for the SafetyNet Range

SafetyNet modules present specific testing challenges due to their dual-channel redundant architecture, safety-rated backplane bus, and onboard self-diagnostic circuits. Standard PLC test benches are insufficient for validating SafetyNet module integrity.

DriveKNMS applies a dedicated test protocol for all SafetyNet inventory:

• Backplane bus integrity check: Validates VME-compatible backplane communication between CPU and I/O slots under simulated load conditions
• Dual-channel cross-check verification: Confirms that both processing channels execute identical logic and that the discrepancy detection circuit triggers correctly on injected faults
• Watchdog timer validation: Tests hardware watchdog response time against GE SafetyNet specification tolerances
• I/O channel isolation test: Each analog and digital channel is tested individually for leakage, response time, and accuracy against datasheet limits
• Communication protocol handshake test: CMM and ETH adapter modules are validated for Modbus RTU frame integrity and SRTP session establishment
• Burn-in cycle: All logic controller modules undergo a minimum 48-hour powered burn-in to screen for early-life component failures